Just be aware that Jan-Feb is in the middle of high season so accommodations will be harder, but surely not impossible, to find. And yes, more is available than you will see online. There are several bulletin boards around town that have accommodations posted that agents won't have. Most will want a longer period than you are suggesting, especially since it will be high season, but you can probably find something in a couple of days.
Agree about Perico, both that it is a good option if available, but it is a few miles outside of 'town' and I am not aware that it is on a bus route. Google Hotel Perico Ajijic

Don't have an answer for you (sorry!) but a question.... do you possibly mean Regenexx as opposed to Regenerix? If so, it's too bad they are closing as that organization is top notch with their protocols here in the States.... main office in 'Denver'.

Switch SIM cards between the two phones and see if the problem "stays with the phone or follows the SIM card"....
To my knowledge there is no "Telcel landline' service at Lakeside. Did you mean TelMex?

I"ve been using Auslogics defrag product for years.... recently it went missing. Norton deleted it. I re-installed, Norton deleted. I checked into why and found that it is doing/allowing bad things as suggested above by CG. And I've never 'trusted' anything to mess with the Registry. Just me, but....
So now I just let Windows 10 do its thing....